PATHOGENIC BACTERIA. 395 



reproduction of the disease in animals is concerned, the neces- 

 sary proof has been supplied by the accidental or intentional 

 infection of laboratory investigators who were working with 

 cholera, which has happened on several occasions. 



Bacteriological investigations have shown that the spirilla of 

 cholera are present in very large numbers in the watery contents 

 of the intestine, especially early in the disease. They appear 

 in the lumina of the glands, and they may be seen underneath 

 the epithelial cells. They may occur in the matters vomited. 

 They have been found in the feces of apparently well persons 

 in times of cholera epidemic. These persons may spread 

 the disease, and are to be regarded as bacillus carriers just as 

 in the case of typhoid fever where healthy persons harbor 

 the bacilli and evacuate them in the stools. They usually 

 are not found widely spread through the organs of the body. 

 It is probable that the symptoms of the disease result from 

 poisonous substances produced by the spirilla or contained 

 in them. 



The portal of entry in cholera is probably always the ali- 

 mentary tract, and the infectious agent is usually, though not 

 always, transmitted through drinking-water, and numerous 

 epidemics have been traced to this source. In some cases the 

 origin of the contamination of the water with cholera dejecta 

 has been demonstrated. The organism may, however, be 

 introduced into the alimentary tract upon any and every 

 article of food. It may be conveyed from place to place upon 

 soiled clothing and bedding, and then be brought in contact 

 with food. Flies also probably convey the organisms from 

 cholera stools to articles of food. In order to combat the 

 spread of the disease the excreta and bedding should be 

 thoroughly sterilized; the hands of the attendants should be 

 carefully disinfected and all food should be cooked. Although 

 commoner in the summer-time, epidemics of cholera have 

 been known to occur in the winter. , 



